Mix 125ml (½ c) of the milk with the flour, cornflour, salt and syrup until smooth. Set aside.

In a saucepan over medium heat, bring the remaining milk to just below boiling point. Remove from the heat and stir in the flour mixture. Return to the heat and stir continuously until the mixture thickens. Add the butter, a little at a time, mixing until well combined. Beat the egg yolks into the warmed milk mixture.